The present disclosure relates generally to equipment useful in operations related to subterranean wellbores, e.g., wellbores employed for oil and gas exploration, drilling and production. More particularly, embodiments of the disclosure relate to components of a drilling assembly that withstand erosive and corrosive wear.
Downhole dulling tools include turbines or Turbodrills, which are high-speed rotating machines used to drive drill bits in hard rock drilling applications. Turbodrills are typically about 10-12 meters in length, with long drive-shafts that transmit the power generated from the drilling fluid passing through the turbine blades to the drill bit. To ensure proper guidance and dynamic control of the rotating shafts mud lubricated radial guide bearings are staged at intervals along the shaft length. Mud lubrication of these bearings is preferred as the mud passing through the tool also cools and flushes the bearing surfaces. Drilling muds generally contain solids materials, which can in themselves be abrasive, but may also contain fine debris recirculated from the drill bit. Consequently, mud lubricated bearings are subject to wear and tear due in part to the presence of abradants in the mud.
Stabilizers are often provided to centralize the turbodrill in the wellbore. The stabilizers protrude from an outer surface of the turbodrill and abrasively engage the wall of the wellbore to help keep the drill bit oriented in a desired direction. As mud is recirculated from the drill bit, the stabilizers are also exposed to mudflow and the associated wear.